| This work aims at studying multi-scale structures of large-scale stratiform precipitating clouds typical of Henan Province of central-eastern China in spring and autumn drought periods of China, the potentials and techniques of artificial rain increase. Through analysis of historical weather/climate and cloud physical data, developed are a number of multi-scale observational schemes including intensive observational items, and space/time resolutions of data for integrative field observations to obtain real-time measurements of the structures at large-, medium-, small- and micro-scale. From analysis of observed separate items, their integrative treatment and numerical simulation we place focus on case studies and their integration in investigating such structures of stratiform precipitating clouds over the target region, rainfall physical mechanisms and exploitation of artificial rainfall increase potentials, whereupon a conceptual model is constructed and a range of catalysis schemes are proposed to improve smaller-scale forecasting accracy and techniques for the rainfall increase, with the dominant results given below.1) The meso - micro-scale soundings and the data processing techniques. Three-dimensional high-density space/time soundings serve as the main body of data consisting of 3-hr interval Doppler probings, 10-30 min rainfall intensity, surface raindrop sizes sampling and GPS-guided flight cloud physics detections with output taken at 2-sec and 200-m intervals. And specific systems associated therewith are developed for multiple-way communication and data collection and storage, a platform for analysis, retrieval softwares for dominant items and multi-scale cloud models - all constitute a system of techniques for meso to microscale observations and analysis.2) Atmospheric water resource and macroscopic rainfall properties in dry periods of spring and autumn of the target region. These seasons are marked by richer atmospheric water mainly below 700 hPa, with 30 - 45% moisture concentrated below 850 hPa. Three passages of vapor transfer are related to the regional precipitation, especially the one carrying water from the Bay of Bengal. Mixed cold and warm cloud portions are favorable for 'catalysis - water supply'. The duration and rainfall-hit area are about half the lifecycle and rainbelt size, respectively. On the whole, the atmospheric conditions are favorable for artificial rain increase.3) Multi-scale strtiform cloud structures and precipitating mechanism. Atmospheric systems responsible for stratiform precipitating clouds in Henan during spring and autumn are low pressure ?cold front, and surface cyclone. Embedded in a large-scale cold front - cyclone are often meso-and small-scale wet thermal/dynamic structures that are uneven, with a huge cold "cushion" at low levels, frequent meso cold surges and related potentially unstable zones at middle levels. And such zones act as an important dynamic condition for low-level water transfer and also a favorable environmental condition for "seeding - water supply". There stronger echoes are detected, meaning that bubble convection develops in the precipitating fields of the clouds that are homogeneous in the main, causing centers of > 10 mm/hr surface rainfall to occur and migrate. The condensates distributed in such clouds are heterogeneous, with high-value cloud water bands located in the midto upper portions, reaching 0.1 g/m3. Rainfall is started mainly in cold portions. Microphysics for ground rainfall consists of low-level warm portions in which precipitating particles are produced, growing through collision with cloud water and when descending into the warm portions below, ice-phase particles melt and continue to grow by collecting cloud water there. 4). Favorable conditions of artificial rain increase and conceptual models for multi-scale rainfall in the study province. The optimal synoptic conditions are mid - high-level trough and a system of trough - cold front with rainfall occurring largely at the rear of the front moving f...
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